Device for electrical stimulation of peridontal complex and surrounding tissue

ABSTRACT

A device for electrical stimulation of one or more components of the periodontal complex and surrounding tissue of a tooth, for uses such as reducing orthodontic pain and encouraging tooth movement, has electrodes of a rigid, electrically conductive material in a fixed spatial relationship configured for application to oral mucosa and attached gingiva adjacent to, and along a periodontal ligament of, a root structure of a single tooth. An electrical circuit is configured for electrical connection to the at least two electrodes. The electrical circuit has an output providing a subsensory electrical stimulus comprising a waveform in accordance with predetermined stimulation parameters. After the electrodes are applied to the oral mucosa and attached gingiva adjacent to, and along the periodontal ligament of, a root structure of the tooth, a switch, when activated, activates the electrical circuit to output the electrical stimulus through the at least two electrodes.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent applicationSer. No. 15/791,462, filed Oct. 24, 2017, pending, which is acontinuation of U.S. patent application Ser. No. 15/147,234, filed May5, 2016, issued as U.S. Pat. No. 9,855,418 on Jan. 2, 2018, which is anonprovisional application of U.S. Provisional Patent Application62/157,053, filed May 5, 2015, expired, all of which are herebyincorporated by reference.

BACKGROUND

A significant and common side effect of orthodontic treatment is painassociated with tooth movement. Orthodontic patients experience painduring or immediately following adjustment of an orthodontic appliance,which may last from two to four days. The pain intensity ranges from aslight soreness when clenching to a constant, throbbing pain. Painassociated with orthodontic treatment is due, at least in part, tocompression of a highly innervated ligament surrounding a tooth.

There are several manners and techniques used today to alleviatepost-adjustment orthodontic pain. Appliances are designed using lighterwires that deliver less force to the teeth. However, many patientscontinue to report discomfort. Other forms of pain relief come from overthe counter pharmacological drugs such as aspirin or other forms of mildanalgesics. Side effects are associated with many of these drugs, andthese drugs sometimes are not effective.

Another challenge in orthodontic treatment is encouraging toothmovement. The overall duration of orthodontic treatment could be reducedif teeth can be encouraged to move more quickly. There are severalmanners and techniques used today to attempt to encourage toothmovement, such as appliances that apply light or vibration.

There are other kinds of pain patients experience due to conditions inthe mouth, such as canker sores, dental pain due to cavities,infections, and procedures, and endodontic pain. Most forms of relieffor such pain are analgesics, antiseptics or numbing agents.

SUMMARY

This Summary introduces selected concepts in simplified form which aredescribed further below in the Detailed Description. This Summary isintended neither to identify essential features, nor to limit the scope,of the claimed subject matter.

A device provides electrical stimulation to one or more components ofthe periodontal complex and surrounding tissue of a tooth, for uses suchas reducing orthodontic or dental pain, encouraging tooth movement, andaddressing other conditions of the periodontal complex. The device haselectrodes of a rigid, electrically conductive material in a fixedspatial relationship configured for application to oral mucosa andattached gingiva adjacent to, and along a periodontal ligament of, aroot structure of a single tooth. An example of such a device is ahandheld device with two electrodes which can be placed on a singletooth at a time by a patient, caretaker or care provider. Anotherexample of such a device is an array of pairs of electrodes, shaped forapplication to multiple teeth, with each pair of electrodes configuredto be applied to a different tooth.

With such a device, an electrical circuit is configured for electricalconnection to the at least two electrodes. The electrical circuit has anoutput providing an electrical stimulus comprising a waveform inaccordance with predetermined stimulation parameters. After theelectrodes are applied to the oral mucosa and attached gingiva adjacentto, and along the periodontal ligament of, a root structure of thetooth, a switch, when activated, activates the electrical circuit tooutput the electrical stimulus through the at least two electrodes. Theelectrical circuit and/or the switch can be housed, along with theelectrodes, in a single integrated housing, or can connect to a housingcontaining the electrodes using a variety of electrical and mechanicalconnections.

In some implementations, the electrical stimulus is designed for thereduction of pain associated with orthodontic tooth movement. In someimplementations, the electrical stimulus is designed for the reductionof dental pain due to cavities, infections, or other conditions orprocedures. In some implementations, the electrical stimulus is designedfor the reduction of endodontic pain due to various conditions orprocedures. In some implementations, the electrical stimulus is designedfor encouraging cellular activity and healing of soft tissue andligaments, to increase or decrease speed of tooth movement. In someimplementations the electrical stimulus is designed to address otherconditions in the mouth, such as canker sores.

In the following description, reference is made to the accompanyingdrawings which form a part hereof, and in which are shown, by way ofillustration, specific example implementations of this technique. It isunderstood that other embodiments may be utilized, and structuralchanges may be made without departing from the scope of the disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an example implementation of a handhelddevice for electrical stimulation a periodontal complex and surroundingtissue of a tooth.

FIG. 2 is a perspective view of an example construction of electrodesfor the device of FIG. 1.

FIG. 3 is a perspective view illustrating electrode placement on oralmucosa and attached gingiva adjacent to, and along a periodontalligament of, a root structure of a tooth.

FIG. 4A is a block diagram of an example implementation of an electricalcircuit that generates an electrical stimulus.

FIG. 4B is a circuit diagram of an example implementation of theelectrical circuit of FIG. 4A.

FIG. 5A is an illustration of an example waveform that can be used as anelectrical stimulus.

FIG. 5B is an illustration of an example waveform that can be used as anelectrical stimulus.

FIG. 6 is a further illustration of the example waveform.

FIG. 7 is a flow chart describing an example process of treatment usingsuch a device.

FIG. 8 is front elevation of another example implementation of a devicehaving an array of electrodes.

FIG. 9 is a side elevation of the implementation of FIG. 8.

FIG. 10 is a side cross-sectional view of the implementation of FIG. 8.

FIG. 11 is a top plan view of the implementation of FIG. 8.

FIG. 12 is a top perspective view of the implementation of FIG. 8.

FIG. 13 is a top perspective cross-sectional view of the implementationof FIG. 8

FIG. 14 is an illustration of an example device in which mechanicalstimulus such as vibration is combined with an electrical stimulus.

FIGS. 15A and 15B are illustrations of example devices in which thermalstimulus such as cooling is combined with an electrical stimulus.

FIG. 16 is an example implementation of a control unit for a device in atabletop embodiment.

FIG. 17 is an example implementation of a handle of the device in thetabletop embodiment.

FIG. 18 is a perspective view of an example implementation of a handhelddevice.

FIG. 19A is a perspective view of an example construction of electrodesfor the device of FIG. 18.

FIG. 19B is a perspective view of an example construction of a tip of ahandle of the device into which the electrodes of FIG. 19A connect.

DETAILED DESCRIPTION

The following detailed description sets forth example implementations ofa device for electrical stimulation of one or more components of theperiodontal complex and surrounding tissue of a tooth, for uses such asreducing orthodontic pain and encouraging tooth movement. The device haselectrodes of a rigid, electrically conductive material in a fixedspatial relationship configured for application to oral mucosa andattached gingiva adjacent to, and along a periodontal ligament of, aroot structure of a single tooth. An electrical circuit applies, throughthe electrodes, a subsensory or slightly sensory electrical stimuluscomprising a waveform in accordance with predetermined stimulationparameters. Examples of such a device described below include a handhelddevice with two electrodes which can be placed on a single tooth at atime by a patient, caretaker or care provider. Another example of such adevice is an array of pairs of electrodes, shaped for application tomultiple teeth, with each pair of electrodes applied to a differenttooth.

A first example implementation of such a device will now be described inconnection with FIGS. 1-3. Additional configurations are shown in FIGS.18 and 19. A second example implementation of such a device is describedbelow in connection with FIGS. 8-13. An example implementation of anelectrical circuit that can be used in either implementation isdescribed below in connection with FIGS. 4A and 4B through 6. Additionalembodiments are shown in FIGS. 14 through 17. A flowchart describing anexample treatment process using either device is described below inconnection with FIG. 7.

In FIG. 1, a device for electrical stimulation of the periodontalcomplex and surrounding tissue of a tooth includes a housing 100configured to be handheld. At least two electrodes 102, 104 of a rigid,electrically conductive material and in a fixed spatial relationship aremounted at a first end 106 of the housing. With this exampleimplementation, when the device is used, the electrodes of the deviceare manually placed on a desired location in the mouth. An electricalcircuit (not shown in FIG. 1), such as described in more detail below inconnection with FIGS. 4A and 4B, is electrically connected to the atleast two electrodes 102, 104. The electrical circuit has an outputproviding, through the at least two electrodes, a subsensory electricalstimulus comprising a waveform in accordance with predeterminedstimulation parameters. A switch 108 is provided which can bemanipulated by a user to activate the electrical circuit to initiate theoutput of the electrical stimulus through the at least two electrodes102, 104.

The electrical circuit and/or the switch can be housed in the housing100 with the electrodes, as shown in FIG. 1, or can connect to a housingcontaining the electrodes using a variety of electrical and mechanicalconnections. The housing can also contain a battery or can be configuredto accept an external power source through an appropriateelectromechanical connection. The housing can be made of, for example,an acrylic or suitable plastic, or other solid material commonly usedfor similar devices. The housing can have a mating cap (not shown) tocover the electrodes when not in use.

As shown in this example implementation, a light 110, such as a lightemitting diode, or other visible element, can be provided on thehousing. When the electrical circuit is activated and is outputting theelectrical stimulus, the light can be used to indicate operation of thedevice. Such a light also can be configured with the electrical circuitto indicate adequate battery power.

In one example implementation, shown in more detail in FIG. 2, the atleast two electrodes comprises two posts 206 of a rigid, electricallyconductive material, such as stainless steel, connected to a base 208.While the posts 206 are illustrated as being straight, the posts can beangled to improve the ability of an operator of the device to reachteeth in the back of the mouth. The electrodes are rigid in the sensethat the electrodes retain their shape and position without an externalforce; however, the electrodes can be made of a material than can bemanipulated, shaped or bent. Several metals, such as stainless steel,are suitable for this purpose. The base can be made of ceramic or otherinsulating material. A tip of each post 206 can be terminated by asphere 200, 202 of an electrically conductive material, such asstainless steel. The sphere and post of an electrode are preferably madeof the same material as a single, integrated piece. Other shapes may beused for the tips, such as flat paddles, rounded tips, or other shapes.The tip size also may vary among applications. The differences in size,shape and number of probes can affect the current density. For example,a larger tip area may be used to apply an initial high current blast,and then a smaller tip area may be used for remaining subsequentstimuli.

While the Figures illustrate two electrodes it should be understood thatat least two electrodes encompass more than two electrodes or probecontacts applied to a tooth. There can be any number of probe contactsapplied to a tooth. The probe contacts can be configured to be appliedto both sides of a tooth. Different numbers and configurations of probecontacts depend on the nerve bundles intended to be affected by thestimulus. Multiple contacts also may result in an effect of the stimulusbeing achieved more quickly.

The tips of the electrodes are in a fixed spatial relationship, asindicated by spacing “S”, which is based on the application of theelectrodes to oral mucosa and attached gingiva adjacent to, and along aperiodontal ligament of, a root structure of a single tooth, asdescribed in more detail below in connection with FIG. 3. Thus, thespacing of the electrodes is such that they can span an adequate lengthalong the periodontal ligament between the attached gingiva and the oralmucosa. For example, the spacing can be at least two millimeters. Asanother example, the spacing can be at least three millimeters. Asanother example, the spacing can be between two millimeters and sixmillimeters. As another example, the spacing can be between three andfive millimeters. As another example, the spacing can be between 3.5 and4.5 millimeters. As another example the spacing can be approximatelyfour millimeters. In an example implementation as shown, each sphere canbe 0.0945 inches or 2.41 mm in diameter, placed about 0.156 inches or3.98 mm center-to-center apart.

The base 208 can have a shape corresponding to an opening 212 formed atthe end of the housing 220, with the opening having a bottom portion222, and the base 208 can be configured to be removable. With such aconstruction, the base has a first mechanical connector having a matingconfiguration with a second mechanical connector of the housing; thebase also has a first electrical connection having a matingconfiguration with a second electrical connection of the housing. Such aconstruction of the housing and electrode interconnection allows forremoval of the electrodes for cleaning or sterilization, forreplacement, or to allow various configurations of electrodes to beused.

In the example shown in FIG. 2, the base can engage electricallyconductive connectors, e.g., 210, which provide for mechanicalengagement of the base 208 with the housing 220, and an electricalconnection to a circuit (not shown in FIG. 2) within the housing. Thecircuit within the housing provides for the electrical connection to theelectrical circuit that generates the electrical stimulus. Moreparticularly, in the example shown in FIG. 2, a bent portion 214 of theconnector 210 engages an area of the base 208 that forms a gap 224 toprovide mechanical engagement; the bent portion 214 also contacts aportion 226 of the post 206 to provide the electrical connection.

Another implementation of a handheld device is shown in FIGS. 18 and 19.In this example, a housing 1800 is configured to be handheld. At leasttwo electrodes 1802, 1804 of a rigid, electrically conductive materialand in a fixed spatial relationship are mounted in a tip base 1820 at afirst end 1806 of the housing. With this example implementation, whenthe device is used, the electrodes of the device are manually placed ona desired location in the mouth. An electrical circuit (not shown inFIG. 18), such as described in more detail below in connection withFIGS. 4A and 4B, is electrically connected to the at least twoelectrodes 1802, 1804. The electrical circuit has an output providing,through the at least two electrodes, an electrical stimulus comprising awaveform in accordance with predetermined stimulation parameters. Aswitch 1808 can be provided which can be manipulated by a user toactivate the electrical circuit to initiate the output of the electricalstimulus through the at least two electrodes 1802, 1804.

The electrical circuit and/or the switch can be housed in the housing1800 with the electrodes as shown in FIG. 18, or can connect to ahousing containing the electrodes using a variety of electrical andmechanical connections, an example of which is shown in FIGS. 16 and 17.The housing can also contain a battery, or can be configured to acceptan external power source through an appropriate electromechanicalconnection. The housing can be made of, for example, an acrylic orsuitable plastic, or other solid material commonly used for similardevices. The housing can have a mating cap (not shown) to cover theelectrodes 1802, 1804 when the device is not in use. The housing 1800may be angled, as shown at 1822, such that a handle portion 1824 is atan angle to a tip portion 1826. Such an angle of the tip portion canimprove the ability of an operator of the device to reach teeth in theback of the mouth.

It should be understood that the size and shape of the housing such asshown in FIGS. 1 and 18 can be different for different applications. Thehandles can be ergonomically designed for hands of different sizes, suchas for children and adults and individuals with disabilities. Thehandles may have written instructions for use or may be adorned with artor images of characters from the movies or books or other types ofdrawings that appeal to intended user.

Turning now to FIG. 19A, the tip base 1900 can have a shapecorresponding to an opening formed at the end of the housing 1800. Thetip base 1900 can be configured to be removable from the housing 1800.As an example of such a construction, the base can have a mechanicalconnector 1902 having a mating configuration with a correspondingmechanical connector of the housing. The connector 1902 provides aflexible, snap-fit into the housing 1800. The tip base 1900 also has afirst electrical connections 1904 having a mating configuration with acorresponding electrical connection of the housing. The correspondingstructure of the handle is shown in FIG. 19B. The first electricalconnections 1904 make contact with second electrical connections 1920and 1922. The connector 1902 snap into a mating structure 1924. It canbe released be inserting a narrow instrument into hole 1926.

Turning now to FIG. 3, placement of the electrodes will now be describedin more detail. While FIG. 3 illustrates application of the electrodesto a facial surface, the electrodes can be placed on any surface of thetissue surrounding the periodontal complex, whether facial, palatal,lingual or buccal surfaces. In use, the two electrodes are placed onoral mucosa 300 and attached gingiva 302 adjacent to, and along (asindicated by dashed line 306) a periodontal ligament of, a rootstructure of a single tooth 304 or on the tooth enamel itself. When theelectrical stimulus is applied from the electrical circuit through theelectrodes so placed on a tooth, the device electrically stimulates oneor more components of the periodontal complex (which includes the tooth,its root nerve, periodontal ligament, and bone) and its surroundingtissue (including gingiva and oral mucosa) of the tooth. Such directelectrical stimulation of one or more components of the periodontalcomplex and surrounding tissue of the tooth, which includes both ahighly innervated ligament that can become compressed and soft tissuewhich can be damaged by orthodontic adjustments and tooth movement, canstimulate the various pathways or mechanisms that relate to pain and/orincreased cellular activity.

Turning now to FIG. 4A, an example implementation of an electricalcircuit will now be described. In FIG. 4A, the electrical circuitincludes a power source 400, such as a battery. The battery may berechargeable. The battery may be removable. As an alternative to, or inaddition to, a battery, an external power source can be used. A“battery” can include one or more batteries, such as button cellbatteries. In one example implementation, a 4.5-volt direct currentsource can be provided by three 1.5-volt button cell batteries.

A switch 402 is used to activate the electrical circuit. For example,the switch 402 can represent a button switch such as shown on the devicein FIG. 1. The switch 402 can include any of a variety of mechanicalswitches, an electromechanical switch, or an electrical switch. Theswitching function can be provided by a control signal from an externalcontroller.

The electrical circuit can include a visual indicator 404, such as alight emitting diode, to indicate whether the electrical circuit isactive. The visual indicator also, or alternatively, can be selected,and the electrical circuit can be designed, so as to indicate batterylevel or other operational state of the device.

The electrical circuit also includes a waveform generator 406. Thewaveform generator is a circuit that generates an electrical stimuluscomprising a waveform in accordance with predetermined stimulationparameters. The output of the waveform generator is applied throughelectrodes 408 and 410. The design of the electrical circuit isdependent on an output waveform and other stimulation parametersdefining the electrical stimulus to be generated for a particularapplication. The predetermined stimulation parameters include at least aform of the output waveform, a pulse frequency of the waveform, and acurrent. A duration of the electrical stimulus also can bepredetermined. The waveform generator is designed to provide the outputwaveform according to its specified form and pulse frequency. Given avoltage that powers the electrical circuit (which may be a nominalvoltage if a battery is used as a power source), a resistance in serieswith the output of the waveform generator is selected to provide thedesired output current.

An example implementation of a circuit of FIG. 4A is shown in FIG. 4B.

In FIG. 4B, outputs VO1 and V02 of the programmable waveform generatorare provided to the probe contacts PC1 and PC2 through an output circuit450. The output circuit is designed to ensure that no direct currentcomponent is output through the probe contacts PC1 and PC2 to theindividual's tissues when in contact with the probe. The circuitincludes a first Zener diode 452 connected between ground and the outputVO1 and a second Zener diode 454 connected between ground and the outputV02. Four resistors of resistance R are provided. A first resistor 456connects in series between output VO1 and a second resistor 458. A thirdresistor 460 connects in series between output VO2 and a fourth resistor462. A first capacitor 464 connects between the junction 466 of firstand second resistors and ground. A second capacitor 468 connects betweenthe junction 470 of first and second resistors and ground. The first andsecond capacitors have capacitance C2. A third capacitor 472 isconnected in series with the second resistor 458 and the probe contactPC1; a fourth capacitor 474 is connected in series with the fourthresistor 462 and the probe contact PC2. The third and fourth capacitorshave capacitance C1. For the purpose of modeling the circuit, a loadresistor 480 represents the load resistance of the tissue when the probecontacts are applied to the tissue. In one implementation, R=110 Ohms,C2=0.01 microfarads, and C1=10 microfarads. The capacitance Clcontributes to reduction of direct current flowing to the patient'stissue.

By having a device with predetermined stimulation parameters, theelectrical stimulus can be ensured to be subsensory, for most patients,and in a form for its desired purpose. With such a configuration,patients can safely use the device.

The duration and/or frequency of application of the electrical stimulusalso can be controlled by the electrical circuit. For example, theelectrical circuit can include one or more timers (not shown in FIG. 4Aor 4B). Such timers can further control activation and deactivation ofthe electrical circuit so that the electrical circuit outputs theelectrical stimulus only for a specified duration. Such timers also canfurther control activation of the electrical circuit so that it cannotbe reactivated until a specified period of time has elapsed. In mostapplications, the duration of a single application is an amount of timegreater than ten seconds and less than twenty minutes.

Generally speaking the electrical stimulus should be subsensory orminimally sensory and therapeutically effective for reducing orthodonticpain and/or encouraging tooth movement. Also the current should bealternating current without a direct current offset so that the netcurrent applied to the body is neutral.

The electrical stimulus is subsensory when the voltage and currentapplied are sufficiently low that there is little or no sensoryperception of the electrical stimulus by the patient. In some cases, apatient may still report feeling a low level of tingling or musclemovement. The electrical stimulus is generally subsensory at a currentof less than 10 milliamperes. In some cases, the electrical stimulus isgenerally less than 60 milliamperes. In some cases, the electricalstimulus is greater than 10 milliamperes and less than 60 milliamperes.

The electrical stimulus is therapeutically effective depending on thebiological mechanism by which analgesia is produced or by which cellularresponse is stimulated. While research has demonstrated that sucheffects occur in humans in response to certain electrical stimuli, theprecise biological mechanisms through which analgesic effects orcellular activity occurs in response to electrical stimulation is notwell known. In some cases, A-delta and A-beta fibers may be stimulatedto block transmission of painful stimuli by small unmyelinated C-fibersin the spinal cord. A-beta fibers appear to be best stimulated at afrequency in the range of about 80 Hz to 130 Hz; A-delta fibers appearto be best stimulated at a frequency in the range of about 2 Hz to 10Hz, and more particularly 2 Hz to 5 Hz. Both types of fibers also appearto be stimulated with a burst mode high frequency (e.g., greater than100 Hz) signal interrupted at a rate of about two to three bursts persecond. In some cases, an endorphin mediated mechanism may be activatedby the electrical stimulus. Yet other biological mechanisms may beaffected by electrical stimulation, such as prevention of formation ofneural pathways which may otherwise form in response to pain in theabsence of such electrical stimulation.

As a particular example, a waveform with a pulse frequency of less than200 kHz and greater than 0.5 Hz, applied with a current in the range of20 microamperes to sixty (60) milliamperes, can be therapeuticallyeffective for pain reduction with an application time of as little asten seconds up to about several minutes per tooth.

More particularly, the frequency range can be between 100 Hz and 200kHz. More particularly, the frequency range can be between 1 kHz and 12kHz. In some cases, the frequency range can be between 12 kHz and 200kHz. In some cases, the frequency range can be greater than 12 kHz. Insome cases, the frequency range can be greater than 1 kHz.

More particularly, the current range can be between 1 milliampere and 60milliamperes. The current range can be between 1 milliampere and 10milliamperes. The current range can be between 10 milliampere and 60milliamperes. More particularly, the current range can be between 5milliamperes and 10 milliamperes. More particularly, the current rangecan be between 5 milliamperes and 60 milliamperes. In some cases, thecurrent can be greater than 5 milliamperes. In some cases, the currentcan be greater than 10 milliamperes. In some cases, the current can beless than 60 milliamperes.

Such an electrical stimulus can be applied whenever a patient sensespain after an orthodontic adjustment. Such treatment typically would beapplied once a day only for one to four days after an orthodonticadjustment. Orthodontic patients could receive a treatment immediatelyfollowing any procedure that may cause discomfort. At such a low levelof current, there is no sensory perception, and is safe for a wide rangeof patients including children.

As another example, for encouraging tooth movement, a waveform with apulse frequency of less than 12 kHz and greater than 0.5 Hz, with acurrent of approximately 20 microamperes to 800 microamperes, and moreparticularly 20 microamperes to 200 microamperes can be therapeuticallyeffective with an application time of between about 10 minutes and 20minutes, for example about 15 minutes. The effective frequency isdependent on the teeth being moved, because bone density is greater inthe mandibular arch than in the maxillary arch. Such an electricalstimulus can be applied several times a day, such as two to four times aday, over a period of several days, such as one to fourteen days. Thewaveform can stimulate the production of osteoclasts in front of a toothin the direction of movement and of osteoblasts behind the tooth in thedirection of movement, to increase the speed of movement, and canstimulate the transformation of osteoblasts into osteocytes, to decreasethe likelihood of tooth movement in the opposite direction.

In one implementation, as an example, the electrical stimulus comprisesa waveform as shown in FIGS. 5A or FIG. 5B and FIG. 6. In FIG. 5A, thiswaveform includes a plurality of envelopes, where each envelope 500includes a plurality of pulses 502 at a pulse frequency, followed by anoff time 504. While FIGS. 5A and 5B show the form of the output waveformas a rectangular waveform, pulses can be sloped, e.g., triangular, orcurved, e.g., sinusoidal. An envelope can have a positive or negativepolarity, i.e., either positive or negative peak voltage. A plurality ofsuch envelopes can be repeated in a sequence, thus providing an envelopefrequency.

As a specific example of such a waveform shown in FIG. 5A, pulses of 44microseconds on followed by 44 microseconds off provide a total pulsewidth of 88 microseconds, and a pulse frequency of about 11363.6 Hz(11.36 KHz). With 17 such pulses, followed by an off time of 1.5milliseconds, in one envelope, the envelope time is about three (3)milliseconds, providing an envelope frequency of about 333.3 Hz.

As another specific example of such a waveform shown in FIG. 5B, pulsesof 50 microseconds on followed by 50 microseconds off provide a totalpulse width of 100 microseconds, and a pulse frequency of about 10 KHz.With 15 such pulses, followed by an off time of 1.5 milliseconds, in oneenvelope, the envelope time is about three (3) milliseconds, providingan envelope frequency of about 333.3 Hz.

The waveform can include a plurality of envelopes at a first, e.g.,positive, polarity, followed a plurality of envelopes at a second, e.g.,negative, polarity. Alternating between positive and negative polaritysignals provides a net current, when applied to the patient, which isneutral. In the implementation shown in FIG. 6, the waveform includes333 envelopes 600 at a positive peak voltage, followed by 333 envelopes602 at a negative peak voltage, to provide one (1) second of a positivesignal and one (1) second of a negative signal. The frequency of thepositive to negative signal transition is thus 0.5 Hz.

With the waveform such as shown in FIGS. 5A, 5B, and 6, and a nominalbattery voltage powering the electrical circuit of about 4.5 volts, anda series resistance of 440 ohms, a nominal maximum output current ofabout 10 milliamps can be provided.

Considering FIGS. 4B and 5B together, the waveform generator produces asequence of 333 instances of the basic waveform shown in FIG. 5B, andpresents that waveform at output port VO1, while setting output port VO2to zero volts. This operation consumes one second. After that, thevoltage at output port VO1 is then set to zero volts and the 333envelops of the basic waveform are output at output port V02. Thisoperation consumes one second. The process is repeated for a desirednumber of seconds. In FIG. 4B, because of the 10 mF series capacitorsC1, the voltage seen between probe contacts PC1 and PC2 swings between anegative value and a positive value. The exact voltage shape seen by theload resistors and absolute values depend on the impedance of the loadresistor.

Turning now to FIG. 7, a flow chart describing an example treatmentprocedure using such a device will now be described. This treatmentprocess can be performed by an orthodontist or other health careprovider, the patient, or a patient's caretaker or parent. Because thedevice generates a fixed, subsensory (for most patients) or minimallysensory electrical stimulus, this process can even be performed by achild patient.

The electrodes of the device are placed 700 on a treatment area in themouth, such as shown in FIG. 3. The electrical circuit for the device isactivated 702, for example by pressing a button of a device such asshown in FIG. 1, to cause the electrical circuit to generate the desiredstimulus. The device generates 704 the stimulus, which is appliedthrough the electrodes to the treatment area. After a period of time,which can be generally about 10 to 60 seconds depending on the conditionbeing treated, the electrodes can be removed 706. During this period oftime that the stimulus is being generated and applied to the tooth, theelectrodes may be moved 705 about the treatment area. Motion of theelectrodes on the treatment area can reduce the likelihood that too muchcurrent would be applied in one spot, to reduce the risk of cellulardamage, and can increase the area in which treatment is provided and thenumber of nerve fibers affected by that treatment. The rubbing of theelectrodes on the tissue may also activate sensory paths and preparenerves for stimulus, similar to a rub or pull technique when giving aninjection. The electrodes can be placed on another treatment area, asindicated at 708, e.g., by repeating the treatment for additional teeth,to allow the stimulus to be applied to address pain in the othertreatment area. When treatment is completed, the device can bedeactivated 710. The device may be activated and deactivated betweentreatments of different treatment areas.

For some orthodontic pain, such as periodontal ligament (PDL) nervepain, the treatment area is the oral mucosa and attached gingivaadjacent to, and along a periodontal ligament of, a root structure of asingle tooth. For this kind of treatment, the electrodes can be moved ina sweeping motion, at a rate of about 5 mm/second. The treatment time isabout 20 seconds. An effective amount of time generally is dependent onthe tooth size.

For some orthodontic pain, such as pulp-related pain from toothmovement, the treatment area can be on the enamel or dentin of a singletooth, primarily on the center of the coronal cusp. For this kind oftreatment, the electrodes generally are held stationary. The treatmenttime is about 20 seconds. An effective amount of time generally isdependent on the tooth size.

For pain from a canker sore or mouth ulcer or aphthous ulcer or otherlesions such as herpetic lesions, the treatment area is the border oredge of the ulcer or lesion. For this kind of treatment, the electrodescan be moved in a sweeping motion, at a rate of about 5 mm/second,around the edge of the ulcer, without making direct contact with theopen wound. The treatment time is about 10 to 20 seconds. An effectiveamount of time generally is dependent on the size of the ulcer.

For some dental pain, such as mild pulpitis, a sensitive exposed root,post-filling sensitivity, post-crown insertion, and pain from a cleaningor polishing, the treatment area can be on the enamel or dentin of asingle tooth, primarily on the center of the coronal cusp. For this kindof treatment, the electrodes generally are held stationary on thecoronal cusp. The treatment time is about 20 seconds. A treatment areafor a secondary application on the same tooth can be at the root apex.For this kind of treatment, the electrodes can be moved in a sweepingmotion, at a rate of about 5 mm/second. The treatment time is about 20seconds. The total treatment time per tooth is about 30 to 60 seconds.

For some dental pain, such as moderate pulpitis, a deep cavity that hasnot penetrated the pulp, root exposure or recession, temperaturesensitivity, and pain from fillings or decay, the treatment area can beon the enamel or dentin of a single tooth, primarily on the center ofthe coronal cusp. For this kind of treatment, the electrodes generallyare held stationary on the coronal cusp. The treatment time is about 20seconds. A treatment area for a secondary application on the same toothcan be at the root apex. For this kind of treatment, the electrodes canbe moved in a sweeping motion, at a rate of about 5 mm/second. Thetreatment time is about 20 seconds. The total treatment time per toothis about 30 to 60 seconds.

For pain due to implant surgery or other endodontic pain, the treatmentarea can be the buccal gingiva, mucosa adjacent the implant, or rootarea of intact soft issue. For this kind of treatment, the electrodescan be moved in a sweeping motion, at a rate of about 5 mm/second. Thetreatment time is about 30-60 seconds. If a tooth canal has not beencompletely de-inervated, direct contact with the enamel or dentin of asingle tooth also can be used. For this secondary treatment, theelectrodes can be moved in a sweeping motion, at a rate of about 5mm/second. The treatment time is about 30-60 seconds.

In some applications, the waveform can be fluctuated or changed duringthe course of treatment. For example, the waveform may be stepped from5000 Hz to 20,000 Hz, for a set period of time for each frequency, suchas several seconds. One reason to fluctuate the frequency is thatdifferent nerve bundles may be responsive to different frequencies dueto different characteristics of these bundles, such as thicknesses ofnerve fibers and myelinated versus unmyelinated.

In some cases, an initial stimulus, followed by a second differentstimulus, can be provided for different treatments. Each type oftreatment may have a different initial stimulus or a different secondstimulus than other treatments. For example, the initial stimulus may bea “silent load” that steadily increases the current so a patient doesnot “detect” the stimulus. As another example, a “block pulse”, with ahigher current and/or higher frequency than subsequent pulses mayincrease potency of an initial pain numbing effect when followed by asteady lower level current with a fluctuating pulse.

Pain relief, stimulation of cellular response, and increased healingrates are not limited to orthodontic treatment. Such a device also canbe used to reduce pain and improve healing times for other conditionsand/or procedures that affect components of the periodontal complex,such as dental conditions and procedures, endodontic conditions andprocedures, implants, and other oral surgery.

Referring now to FIGS. 8-13, a second example of an implementation ofsuch a device for electrical stimulation of one or more components of aperiodontal complex and surrounding tissue of multiple teeth, will nowbe described. In this implementation, an array of pairs of electrodes isused to apply electrical stimulation to components the periodontalcomplexes of multiple teeth. Such an array is particularly useful forencouraging tooth movement throughout the entire mouth, but also can beused for pain reduction. In this device, the principle of electricalstimulation, the stimulation parameters of the electrical stimulus usedfor treatment, and corresponding electrical circuit for generating theelectrical stimulus, are similar to those of a device for treating asingle tooth. In FIG. 8, an array of electrodes can deliver theelectrical stimulus to multiple teeth. The electrical circuit can bedesigned to drive all pairs of electrodes simultaneously, or all pairsof electrodes in a subset can be driven simultaneously with each subsetbeing driven in sequence, or individual pairs of electrodes can bedriven in sequence, or an individual pair of electrodes can be selectedand driven with the electrical stimulus.

FIG. 8 is front elevation of this example implementation of the devicehaving an array of electrodes. FIG. 9 is a side elevation of the exampleimplementation of FIG. 8. FIG. 10 is a side cross-sectional view of theexample implementation of FIG. 8. FIG. 11 is a top plan view of theexample implementation of FIG. 8. FIG. 12 is a top perspective view ofthe example implementation of FIG. 8. FIG. 13 is a top perspectivecross-sectional view of the example implementation of FIG. 8.

In this example implementation of the device, a housing 800 is shaped tobe placed around teeth along a jaw of a patient. The housing can bedesigned to encapsulate the electromechanical components in a hermeticpackage made from biocompatible materials suitable for long termintra-oral use. In this example implementation, the housing has a firstportion 802 for a top set of teeth, and a second portion 804 for abottom set of teeth. A flexible portion 806 allows the device to befolded for placement in the mouth. A plurality of pairs 808 ofelectrodes in a fixed spatial relationship are mounted at locationsalong an internal face 810 of the housing corresponding to positions ofthe teeth along the jaw. The electrodes shown in this exampleimplementation are in the form small hemispherical objects ofelectrically conductive material, such as stainless steel, and having asubstantially flat surface facing the soft tissue to which they will beapplied. Such electrodes can be about the same size as the spheres shownabove in FIG. 2. When the housing is placed in the mouth and surroundingthe teeth along the jaw, each pair of electrodes is placed in contactwith oral mucosa and attached gingiva adjacent to, and along aperiodontal ligament of, a root structure of its corresponding tooth. Anelectrical circuit, such as shown in FIGS. 4A and 4B, can be connectedto the housing 800 through an electromechanical interface 820 and wires822 (shown in FIG. 10) to deliver the electrical stimulus to the pairsof electrodes. Such a design can be embodied in retainers, an example ofwhich is shown in U.S. Pat. No. 10,098,710, mouthguards and othersimilar devices.

Referring now to FIG. 14, an example device in which mechanicalstimulus, such as vibration, is combined with an electrical stimuluswill now be described. For example, an electromechanical device can beconnected to the electrodes, or the base housing the electrodes, orwithin the housing of the device. In one implementation, theelectromechanical device can be a vibration motor, such as a linearresonant actuator, a housing for the electrodes of the device. In FIG.14, an example implementation of an electrical circuit includes awaveform generator 1406 that generates the electrical stimulus. Acontroller 1404 can control operation of the waveform generator and avibration motor 1402 (shown in slight perspective) which is connected toa housing 1400 for the electrodes of the device. The output of thewaveform generator is applied through electrodes 1408 and 1410. Avibration motor 1402 is connected to a housing for the electrodes, and,when activated by the controller 1404, generates a vibration whichpropagates through the housing to the electrodes.

Referring now to FIGS. 15A and 15B, an example device in which thermalstimulus, such as cooling, is combined with an electrical stimulus willnow be described. For example, a thermoelectric device can be connectedto one or more of the electrodes. In one implementation, thethermoelectric device can be a solid-state device having two differentmaterials forming a junction capable of exhibiting the Peltier effect.When an electrical current flows in this device across the junction, thedevice acts as an active heat pump which transfers heat from one side ofthe device to another side of the device, depending on the direction ofthe current flow. In FIG. 15A, an example implementation of anelectrical circuit includes a waveform generator 1506 that generates theelectrical stimulus. The output of the waveform generator is appliedthrough electrodes 1508 and 1510. A thermoelectric device 1500 isconnected to the base to cause transfer thermal energy with the tip baseand the housing. Another way of providing a thermal stimulus is to heator cool the electrodes, using any technique typically used for dental ororthodontic applications, prior to applying the electrodes duringtreatment. Yet another option is to wrap the electrodes 1528, 1530 in atubing 1520 through which chilled or heated water flows to cool or heatthe probe tips as desired, as demonstrated in FIG. 15B. The tubing canhave an inlet 1522 into which chilled or heated water or other fluid canflow, and an outlet 1524 from which the fluid can flow. A separate pump(not shown) can be used to cause the fluid to flow, and any conventionalthermal system can be used to chill or heat the fluid.

Turning to FIGS. 16 and 17, in this embodiment, the device can beplugged in to a power source, such as a typical outlet in a home oroffice, using a plug 1610 so there is no need for batteries.Alternatively, the housing 1600 can include replaceable batteries. Sucha system includes a control unit (FIG. 16) having a housing 1600 whichcontains the electronics, and a hand held unit (FIG. 17) which supportsthe electrodes 1700 and 1702. The electrodes can be encased in a handle1704, e.g., made of plastic. At one end of the handle, long wires 1706,e.g., about 10 to 20 cm in length or longer, connect to the wires 1604from the control unit in the housing 1600. A connector (not shown) canbe provided anywhere between the housing 1600 and the handle 1704 toallow the handle, and optionally the wires between the handle 1704 andthe housing 1600, to be connected to and disconnected from the housing1600. This housing 1600 could be shaped to allow it to rest on the flooror tabletop or other surface. The housing can have buttons 1620 to allowfor selection of different treatment types, for example indicated bylabels 1622 on the housing. In response to the user pressing one of thebuttons, the circuit is set to generate the corresponding waveform.

In these implementations, the electrodes are separate from the housingcontaining the electronics. The electrodes could be permanently attachedto a short cable which in turn is attached to a longer one that connectsto the housing containing the electronics. In this configuration, boththe electronics and the electrodes can be made reusable for differentpatients by being able to autoclave the electrodes and their cables.This is possible if the cables have, as an example, a Teflon coatingwhich is electrically insulating and chemically inert. Autoclavetemperature is around 121 degrees C., and Teflon generally retains itsintegrity up to 250 degrees C.

Such a device also can be configured for long term placement duringorthodontic treatment. Electrodes can be placed, and then connected viawires to a device containing the electrical components that generate thedesired electrical stimulus.

Other implementations of devices providing electrical stimuli includearrays shaped as a pacifier on which pairs of electrodes are placed atspacings corresponding to individual teeth, such as in an infant's ortoddler's mouth. Such a device can help relieve teething or tootheruption pain of small children.

There are several additional benefits to a patient from using a devicesuch as described herein in connection with orthodontic treatment toelectrically stimulate components of the periodontal complex affected bythe orthodontic treatment. For example, a reduction in pain experiencedby a patient may lead the patient to have better oral hygiene andcompliance with other instructions of the orthodontist. Also, manypatients may otherwise avoid orthodontic treatment because of pain thatis known to be associated with such treatment. The ability to offer morecomfortable orthodontic treatment may enable an orthodontist to provideservices for previously apprehensive patients. The use of electricalstimulation for pain reduction also may decrease the amount ofanalgesics consumed by patients. Also, to the extent that electricalstimulation is used in orthodontic treatment to encourage tooth movementand/or tissue growth, such stimulation may improve the healing timeassociated with tooth movement and may reduce overall treatment time.

It should be understood that the subject matter defined in the appendedclaims is not necessarily limited to the specific implementationsdescribed above. The specific implementations described above aredisclosed as examples only.

What is claimed is:
 1. A device for electrical stimulation of one ormore components of a periodontal complex and surrounding tissue of atooth, comprising: at least two electrodes of a rigid, electricallyconductive material in a fixed spatial relationship configured forapplication to oral mucosa and attached gingiva adjacent to, and along aperiodontal ligament of, a root structure of a single tooth; anelectrical circuit configured for electrical connection to the at leasttwo electrodes, the electrical circuit having an output providing anelectrical stimulus comprising a waveform in accordance with stimulationparameters.
 2. The device of claim 1, wherein the electrical stimulus isa therapeutically effective electrical stimulus for a periodontalcomplex of a tooth.
 3. The device of claim 2, wherein the electricalstimulus is a therapeutically effective electrical stimulus forrelieving periodontal pain.
 4. The device of claim 2, wherein theelectrical stimulus is a therapeutically effective electrical stimulusfor affecting tooth movement.
 5. The device of claim 1, furthercomprising a housing configured to be handheld and wherein the at leasttwo electrodes are mounted in a first end of the housing.
 6. The deviceof claim 5, wherein the at least two electrodes comprises: a base havinga first mechanical connector and a first electrical connection, whereinthe at least two electrodes are mounted in the base; and wherein thehousing has a second mechanical connector having a mating configurationwith the first mechanical connector of the base and a second electricalconnection having a mating configuration with the first electricalconnection of the base; whereby the base is removably connectable to thehousing.
 7. The device of claim 5, wherein the electrical circuit ismounted in the housing.
 8. The device of claim 6, wherein the electricalcircuit is mounted in the housing and the output of the electricalcircuit is connected to the second electrical connection of the housing.9. The device of claim 1, wherein the switch is a mechanical switch. 10.The device of claim 1, wherein the switch is an electromechanicalswitch.
 11. The device of claim 1, wherein the switch is a controllerconfigured to activate the electrical circuit.
 12. The device of claim1, wherein the waveform comprises a plurality of pulses having a pulsefrequency.
 13. The device of claim 12, wherein the waveform comprises afirst plurality of pulses of a positive polarity at the pulse frequencyin a first envelope, and a second plurality of pulses of a negativepolarity at the pulse frequency in a second envelope, and a transitionbetween the first and second plurality of envelopes occurring at atransition frequency.
 14. The device of claim 12, wherein the pulsefrequency is in a range of 1 kHz to 12 kHz.
 15. The device of claim 1,wherein the predetermined stimulation parameters comprises a current ofthe electrical stimulus, and wherein the current is less than tenmilliamperes.
 16. The device of claim 1, wherein the predeterminedstimulation parameters comprises a duration of the electrical stimulus,and wherein the duration is an amount of time greater than ten secondsand less than twenty minutes.
 17. A device for electrical stimulation ofone or more components of periodontal complexes and surrounding tissuesof a plurality of teeth, comprising: a housing shaped to be placedaround the plurality of teeth; a plurality of pairs of electrodes in afixed spatial relationship, mounted at locations along the housingcorresponding to positions of the teeth, such that, when the housing ispositioned to surround the plurality teeth, each pair of electrodes isplaced in contact with oral mucosa and attached gingiva adjacent to, andalong a periodontal ligament of, a root structure of corresponding oneof the plurality of teeth; an electrical circuit configured forelectrical connection to the plurality of pairs of electrodes, theelectrical circuit having an output providing an electrical stimuluscomprising a waveform in accordance with stimulation parameters.
 18. Aprocess for electrical stimulation of one or more components of aperiodontal complex and surrounding tissue of a tooth, comprising:placing electrodes of a device on oral mucosa and attached gingivaadjacent to, and along a periodontal ligament of, a root structure of asingle tooth, the electrodes comprising at least two electrodes of arigid, electrically conductive material in a fixed spatial relationshipconfigured for application to oral mucosa and attached gingiva adjacentto, and along a periodontal ligament of, a root structure of a singletooth; and activating the device to generate an electrical stimuluswhile the electrodes of the device are placed.
 19. The process of claim18 further comprising moving the electrodes on the gingiva and along aperiodontal ligament of, a root structure of a single tooth.
 20. Theprocess of claim 18 further comprising maintaining the electrodessubstantially stationary.